Bottom Line:
Affymetrix Microarray analysis for mRNA expression data reveals expression of inflammatory mediators that are known to be released by activated microglia.Microglia-specific cell surface molecules, including CD11b, CD74, CD52 and CD68, are significantly upregulated in contrast to CD4, CD8 and CD19.Protein analysis of spinal cord extracts taken from mice 6 days post-inoculation, the time of peak inflammation, reveals robust expression of IFN-γ, IL-12 and mKC.

ABSTRACTNeurotropic recombinant strain of Mouse Hepatitis Virus, RSA59, induces meningo-encephalitis, myelitis and demyelination following intracranial inoculation. RSA59 induced neuropathology is partially caused by activation of CNS resident microglia, as demonstrated by changes in cellular morphology and increased expression of a microglia/macrophage specific calcium ion binding factor, Iba1. Affymetrix Microarray analysis for mRNA expression data reveals expression of inflammatory mediators that are known to be released by activated microglia. Microglia-specific cell surface molecules, including CD11b, CD74, CD52 and CD68, are significantly upregulated in contrast to CD4, CD8 and CD19. Protein analysis of spinal cord extracts taken from mice 6 days post-inoculation, the time of peak inflammation, reveals robust expression of IFN-γ, IL-12 and mKC. Data suggest that activated microglia and inflammatory mediators contribute to a local CNS microenvironment that regulates viral replication and IFN-γ production during the acute phase of infection, which in turn can cause phagolysosome maturation and phagocytosis of the myelin sheath, leading to demyelination.

Mentions:
More detailed immunohistochemical analysis of RSA59 infected brain revealed that there are several nodule formations in inflamed regions like basal forebrain, anterior commissure basal pons, midbrain and deep cerebellar white matter at day 6 post-inoculation. Nodules surrounding inflamed regions stain positive for Iba-1 (microglia marker) and inflammatory responses include changes in microglia morphology-from ramified (resting) to amoeboid (active) (Figure 5C and E), which suggests transformation of resting microglia to phagocytotic microglia. In the mock infected brains, most Iba-1 stained cells show ramified morphology characteristic of resting microglia (Figure 5B and D). Very few cells in the vicinity of the inflamed regions are CD4+, CD8+ or CD19+ (data not shown) as seen in previous studies [10], [15]. Data is consistent with mRNA expression by RT- PCR showing a 4- to 5-fold upregulation of the Aif1 gene which encodes Iba-1 protein (Figure 5C).

Mentions:
More detailed immunohistochemical analysis of RSA59 infected brain revealed that there are several nodule formations in inflamed regions like basal forebrain, anterior commissure basal pons, midbrain and deep cerebellar white matter at day 6 post-inoculation. Nodules surrounding inflamed regions stain positive for Iba-1 (microglia marker) and inflammatory responses include changes in microglia morphology-from ramified (resting) to amoeboid (active) (Figure 5C and E), which suggests transformation of resting microglia to phagocytotic microglia. In the mock infected brains, most Iba-1 stained cells show ramified morphology characteristic of resting microglia (Figure 5B and D). Very few cells in the vicinity of the inflamed regions are CD4+, CD8+ or CD19+ (data not shown) as seen in previous studies [10], [15]. Data is consistent with mRNA expression by RT- PCR showing a 4- to 5-fold upregulation of the Aif1 gene which encodes Iba-1 protein (Figure 5C).

Bottom Line:
Affymetrix Microarray analysis for mRNA expression data reveals expression of inflammatory mediators that are known to be released by activated microglia.Microglia-specific cell surface molecules, including CD11b, CD74, CD52 and CD68, are significantly upregulated in contrast to CD4, CD8 and CD19.Protein analysis of spinal cord extracts taken from mice 6 days post-inoculation, the time of peak inflammation, reveals robust expression of IFN-γ, IL-12 and mKC.

ABSTRACTNeurotropic recombinant strain of Mouse Hepatitis Virus, RSA59, induces meningo-encephalitis, myelitis and demyelination following intracranial inoculation. RSA59 induced neuropathology is partially caused by activation of CNS resident microglia, as demonstrated by changes in cellular morphology and increased expression of a microglia/macrophage specific calcium ion binding factor, Iba1. Affymetrix Microarray analysis for mRNA expression data reveals expression of inflammatory mediators that are known to be released by activated microglia. Microglia-specific cell surface molecules, including CD11b, CD74, CD52 and CD68, are significantly upregulated in contrast to CD4, CD8 and CD19. Protein analysis of spinal cord extracts taken from mice 6 days post-inoculation, the time of peak inflammation, reveals robust expression of IFN-γ, IL-12 and mKC. Data suggest that activated microglia and inflammatory mediators contribute to a local CNS microenvironment that regulates viral replication and IFN-γ production during the acute phase of infection, which in turn can cause phagolysosome maturation and phagocytosis of the myelin sheath, leading to demyelination.